Arch enemy uses the melodic minor scale heavily in the chorus of Vultures. Basically, it gives the chorus a little burst of tension and breaks up some of the pure melody that would be heard otherwise. That being said, despite the melodic minor being non-diatonic, there is still a sense of melody and empowerment to the chorus. The melodic minor, in this context, can be viewed as adding a little extra grit to a melodic passage without totally going into intense dissonance.
